<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>测试的拖拽功能</title>
<style type="text/css">
body, div { margin: 0; paading: 0; font-size: 12px; }
body { width: 960px; margin: 0 auto; }
ul, li { margin: 0; padding: 0; list-style: none; }
.clear { clear: both; width: 1px; height: 0px; line-height: 0px; font-size: 1px; }

.box { width: 600px; height: auto; margin: 25px 0 0 0; padding: 5px; border: 1px solid #f00; }
.main { position: static; width: 600px; height: 80px; margin-bottom: 5px; border: 1px solid blue; background: #ccc; }
.maindash { position: absolute; width: 600px; height: 80px; margin-bottom: 5px; border: 1px dashed blue; background: #ececec; opacity: 0.7; }

.hide { width: 600px; height: 80px; margin-bottom: 5px; }
.dash { position: sta;tic; width: 600px; height: 80px; margin-bottom: 5px; border: 1px dashed #f00; };
</style>
<script type="text/javascript" src="jquery.js"></script>
<script type="text/javascript">

$(document).ready( function () {

    var range = { x: 0, y: 0 };//鼠标元素偏移量
    var lastPos = { x: 0, y: 0, x1: 0, y1: 0 }; //拖拽对象的四个坐标
    var tarPos = { x: 0, y: 0, x1: 0, y1: 0 }; //目标元素对象的坐标初始化

    var theDiv = null, move = false;//拖拽对象 拖拽状态
    var theDivId =0, theDivHeight = 0, theDivHalf = 0; tarFirstY = 0; //拖拽对象的索引、高度、的初始化。
    var tarDiv = null, tarFirst, tempDiv;  //要插入的目标元素的对象, 临时的虚线对象

    $(".main").each(function(){
        $(this).mousedown(function (event){
            //拖拽对象
            theDiv = $(this);

            //鼠标元素相对偏移量
            range.x = event.pageX - theDiv.offset().left;
            range.y = event.pageY - theDiv.offset().top;

            theDivId = theDiv.index();
            theDivHeight = theDiv.height();
            theDivHalf = theDivHeight/2;
            move = true;

            theDiv.attr("class","maindash");
            // 创建新元素 插入拖拽元素之前的位置(虚线框)
            $("<div class='dash'></div>").insertBefore(theDiv);

        });
    });

    $(document).mousemove(function(event) {

        if (!move) return false;

        lastPos.x = event.pageX - range.x;
        lastPos.y = event.pageY - range.y;
        lastPos.y1 = lastPos.y + theDivHeight;

        // 拖拽元素随鼠标移动
        theDiv.css({left: lastPos.x + 'px',top: lastPos.y + 'px'});
        // 拖拽元素随鼠标移动 查找插入目标元素

        var  $main = $('.main'); // 局部变量：按照重新排列过的顺序  再次获取 各个元素的坐标，
        tempDiv = $(".dash"); //获得临时 虚线框的对象

        $main.each(function () {
            tarDiv = $(this);
            tarPos.x = tarDiv.offset().left;
            tarPos.y = tarDiv.offset().top;
            tarPos.y1 = tarPos.y + tarDiv.height()/2;

            tarFirst = $main.eq(0); // 获得第一个元素
            tarFirstY = tarFirst.offset().top + theDivHalf ; // 第一个元素对象的中心纵坐标

            //拖拽对象 移动到第一个位置
            if (lastPos.y <= tarFirstY) {
                    tempDiv.insertBefore(tarFirst);
            }
            //判断要插入目标元素的 坐标后， 直接插入
            if (lastPos.y >= tarPos.y - theDivHalf && lastPos.y1 >= tarPos.y1 ) {
                tempDiv.insertAfter(tarDiv);
            }

        });

    }).mouseup(function(event) {

        theDiv.insertBefore(tempDiv);  // 拖拽元素插入到 虚线div的位置上
        theDiv.attr("class", "main"); //恢复对象的初始样式

        $('.dash').remove(); // 删除新建的虚线div
        move=false;

    });

});


</script>
</head>

<body>
<div class="box" id="box">
    <div class="main" id="main0">div1</div>
    <div class="main" id="main1">div2</div>
    <div class="main" id="main2">div3</div>
    <div class="main" id="main3">div4</div>
    <div class="main" id="main4">div5</div>
</div>
</body>
</html>